can we change a background thread operation to main thread?

Question

How can i perform a JSON parsing in background thread in viewDidLoad and move it to main thread when clicks on a button. Now i tried

[self performSelectorInBackground:@selector(parseData) withObject:nil];


-(void)parseData    {

    MSJsonParser *parser = [[MSJsonParser alloc]initWithParserType:kCountriesParsing];
    parser._parserSource = self;
    [parser requestParsingWithUrl:COUNTRIES_URL ];

}

But i dont know how to change this background process to main thread. please help me

Answer 1

The part in that method you want to run on the main thread, just stick it inside this GCD block and it will run it on the main thread:

dispatch_sync(dispatch_get_main_queue(), ^{
    //put stuff here
});

Answer 2

See NSObject (NSThreadPerformAdditions) in NSThread

 - (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)arg waitUntilDone:(BOOL)wait modes:(NSArray *)array;
 - (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)arg waitUntilDone:(BOOL)wait;